Lubricant

ABSTRACT

LUBRICANTS ARE DESCRIBED FOR HYDRAULIC FLUIDS WHICH DO NOT CONSIST OF MINERAL OIL AND CONTAIN MINOR OR MAJOR PROPORTIONS OF WATER. SUCH LUBRICANTS ARE COMPOUNDS CORRESPONDING TO THE GENERAL FORMULA   X=P(-CH2-O-(CH(-R)-CH2-O)N-H)3   IN WHICH X STANDS FOR S OR O, R IS CH3 OR H AND N HAS THE MEANING 0-5/3. THE COMPOUNDS ARE, THUS TRIS-(HYDROXYMETHYL)-PHOSPHINE OXIDE OR SULFIDE AND THE OXALKYLATION PRODUCTS THEREOF WHICH CONTAIN UP TO 5 ETHYLENE OXIDE OR PROPYLENE OXIDE UNITS PER MOLECULE. PRACTICALLY TECHNICAL GRADE OXALKYLLATION PRODUCTS ARE USE WHICH CONTAIN AN AVERAGE OF 0 TO 5 MOLES OF ALKYLENE OXIDE PER MOLE, AND CONSEQUENTLY N MAY STAND FOR ANY VALUE WITHIN THE DEFINED LIMITS.

May 25, 1971 P. GEYMAYER T L LUBRI CANT 2 Sheets-Sheet 1 Filed Sept. 2, 1969 oo E9 009 F GE INVENTORS N E E 5 950 m E l E M YN AE u R EBE G N R REE E Tm G E S V. B

ATTORNEYS May 25, 1971 5 ETAL 3,580,849

LUBRICANT Filed Sept. 2, 1969 2 Sheets-Sheet abrasion 25kg/100m HSC- -- HSC- 4+ 3%TOMP-oxide 560 who rbm INVENTORS PETER GEYMAVER SIEGFRIED BILLENSTEIN WERNER RENZ ATTORNEYS United States Patent 3,580,849 LUBRICANT Peter Geymayer and Siegfried Billenstein, Burgkirchen (A12), and Werner Renz, Burghausen, Salzach, Germany, assignors to Farbwerke Hoechst Aktiengesellschaft vormals Meister Lucius & Bruning, Frankfurt am Main, Germany Filed Sept. 2, 1969, Ser. No. 854,599 Claims priority, application Germany, Sept. 5, 1968, P 17 94 094.2 Int. Cl. C09k 3/00; C10m 3/42; C07f 9/50 U.S. Cl. 252-78 Claims ABSTRACT OF THE DISCLOSURE Lubricants are described for hydraulic fluids which do not consist of mineral oil and contain minor or major proportions of water. Such lubricants are compounds corresponding to the general formula in which X stands for S or O, R is CH or H and n has the meaning 0-5/ 3. The compounds are, thus, tris-(hydroxymethyl)-phosphine oxide or sulfide and the oxalkylation products thereof which contain up to ethylene oxide or propylene oxide units per molecule. Practically technical grade oxalkyllation products are used which contain an average of O to 5 moles of al'kylene oxide per mole, and consequently It may stand for any value within the defined limits.

The present invention relates to lubricants for hydraulic fluids.

As media for hydraulic power transmissions (brakes, torque converters, hydraulic drives) there are used, besides mineral oils, on the one hand, mixtures of glycols and glycol ethers and ester mixtures also in aqueous systems, on the other. Mineral oil-free hydraulic fluids, for example glycol-water mixtures, are preferably used in case the use of difficulty inflammable hydraulic media is required, for example in mining and metallurgy. A serious drawback of liquids of this type is their poor protection property against wear. When operated in liquids of this type, roller bearings and ball bearings, for example, have only 12 to 15% of the working life they could reach with the use of hydraulic oils on the basis of mineral oils.

It has been proposed to improve the high pressure properties of mineral oils by adding certain chemical ingredients. For this purpose there are preferably used sulfurhalogen compounds or phosphorus containing compounds (esters of phosphoric acid, thiophosphoric acid, chloroparaflins and the like). As emergency lubricants these compounds react at elevated temperatures with the metal surfaces with the formation of viscous, firmly adhering layers which prevent seizing (of. G. H. Gottner Einfiihrung in die Schmiertechnik, 2nd part, Karl-Marklein Verlag, 1966).

Most of the high pressure additives used for mineral oils are insoluble in other systems or they are unsuitable in the presence of water owing to their high corrosivity.

It has now been found that the protection against wear of actuating fluids for hydraulically operated mechanisms consisting of mixtures of glycols and polyglycols and/or their ethers or the aqueous solutions thereof can be improved by adding 0.15 to 20% by weight, preferably 1 to 8% of tris(hydroxymethyl)-phosphineoxide and/ or phosphine sulfide as well as the oxal-kylation products thereof with up to 5 moles of ethylene oxide and/or propylene oxide per mole of phosphine oxide or phosphine sulfide.

3,580,849 Patented May 25, 1971 ice The phosphine derivatives to be added are compounds of the general formula in which X stands for S or O, R means CH or H and n is 0-5/ 3.

With regard to the degree of oxalkylation n (of from 0 to 5/3) the following compounds can be used:

The aforesaid oxalkylation products are mostly used in the form of their technical mixtures.

To test the lubricating properties of the actuating fluids according to the invention the four ball apparatus of G. D. Boerlage was used. In this test the protection against wear is defined by two characteristic values, i.e.

(a) Corrected average load according to Hertz. (b) Welding load.

EXAMPLE 1 Polyethylene glycol having a molecular weight of 200 [PEG 2001 was mixed with varying amounts of tris (hydroxymethyl)phosphine oxide (TOMP oxide). The

1 Third report about the requirements and tests of difiicultly inflammable liquids for hydraulic power transmission and steering; committee of the European Communities, permanent committee for operating security in coal mining, Luxembourg Oct. 10, 1967.

2 Study group for the exploitation of literature about lubricants, report N0. 267, pages 1-3, Kadmer (1957).

welding loads measured in the four ball apparatus increased with increasing amounts of additive.

Added amount of TOMP Welding oxide to PEG 200%: load, kg. 140/160 1 160/180 3 I 180/200 5 240/260 7 260/280 EXAMPLE 2 Increasing amounts of TOMP oxide were added to a 50% solution of polyethylene glycol having a molecular weight of 4000 in water. The addition considerably improved the weldin loads measured in the four ball apparatus.

EXAMPLE 3 By adding 2% of T O-MP oxide to a mixture of 65% of PEG 200, 34% of PEG 300, 0.1% of NaNO;,, and 0.9% of borax the welding load measured in the four ball apparatus could be raised from 230/250 kg, to 500/550 kg. and the average load according to *Hertz could be improved from 40.0 kg. to 86.0 kg.

EXAMPLE 4 By adding TOMP oxide to difliculty inflammable hydraulic fluids on the basis of glycol and water the lubricating properties of the said fluids, measured in the four ball apparatus and in the abrasion balance according to Reichert, could be considerably improved. The hydraulic fluids used had different viscosities and consisted of (a) to 30% of liquid, high molecular weight, watersoluble oxalkylation mixture, for example polyglycols having a molecular weight of from 10,000 to 20,000.

(b) 25 to 35% of low molecular weight alkylene glycols and/or alkylene glycol ethers, for example monoethylene glycol, and/or ethylpolyglycol,

(c) 40 to 50% of water,

(d) Various additives for example borax, triethanol amine or morpholine to improve the properties such as protection against corrosion, ageing and the like.

According to the third Luxembourg report (cf. first footnote) difficulty inflammable fluids for hydraulic power transmissions and steering are designated by the initials HS. The letter C indicates the class of the aqueous solutions containing 40 to 50% of water. The number placed behind defines the viscosity, for example HS C2: 11-14 centistokes at 50 C. HS C-4: -40 centistokes at 50 C. HS C-8: 50-70 centistokes at 50 C.

The fluids used in this example essentially correspond Y to the standards defined in the above report. By adding the claimed lubricants the properties of the actuating fluids for hydraulicly operated mechanisms are modified to a negligible degree except for the lubricating properties.

In the accompanying diagrams there are plotted in FIG. 1 the running under load and in FIG. 2 the running which acceleration on the abrasion balance according to Reichert of HS C-4 without addition (full line) and HS C-4 with 3% of TOMP oxide (broken line). In the running under load test the abrasion is determined with increasing load and constant number of revolutions whereas in the running 'With acceleration test the abrasion is determined under a constant load and with increasing number of revolutions.

EXAMPLE 5 A hydraulic fluid of the type HS C-4 was mixed with different oxalkylated TOMP oxides. In the following table there is indicated the influence of the additions on the welding load determined in the four ball apparatus.

Addition: Welding load, kg.

Without addition /180 3% (TOMP oxide plus 1 mole ethylene oxide) 220/240 3% (TOMP oxide plus 1.5 moles ethylene oxide) 200/220 3% (T OMP oxide plus 2.7 moles ethylene oxide) 200/220 3% (TOMP oxide plus 1 mole propylene oxide) 200/220 3% (TOMP oxide plus 1.65 moles propylene oxide) 200/220 3% (TOMP oxide plus 22 moles propylene oxide) 18 0/ 200 EXAMPLE 6 3% of tris(hydroxymethyl)-phosphine sulfide were added to a hydraulic fluid of the type I-IS C-4. By the addition the welding load in the four ball apparatus could be increased from 160/ kg. to 300/320 kg.

What is claimed is:

1. In an aqueous glycol-based hydraulic fluid, the improvement which comprises having present in said fluid a minor proportion of a lubricant of the general formula in which X stands for S or O, R is CH or H, and n has the meaning 0-5/3, in an amount of from 0.1 to 20% By weight, calculated on the total amount of hydraulic I uid.

2. A hydraulic fluid as claimed in claim 1, which contains in addition a corrosion inhibitor.

References Cited UNITED STATES PATENTS 2,462,694 2/ 1949 Walker 25278X 3,267,149 8/1966 Garner 25249.8X 3,404,187 10/1968 Kober et al 260606.5P

LEON D. 'ROSDOL, Primary Examiner D. SILVERSTEIN, Assist-ant Examiner U.S.Cl.X.R. 

